A suicide car bomb exploded at an Iraqi army recruiting centre in Baghdad yesterday, killing 47 people and taking the 24-hour death toll in attacks against Iraqis working with the US occupation forces to 100.

Most of the latest victims were newly recruited soldiers reporting for duty.

"It was a suicide attack by a single male," US officer Colonel Ralph Baker said at the scene.

"It was aimed strictly at Iraqis," Colonel Baker said, adding that the car was laden with plastic explosives mixed with artillery shells to maximise the "kill effect".

Another US officer put the death toll at at least 36, including the bomber, with 15 more injured, but hospitals later said they had received 44 dead and 35 wounded, three of whom died from their wounds.

About 50 people were killed on Tuesday in a similar attack on Iraqis outside a police station south of Baghdad.

The police force and new army are central to Washington's plan to hand over power to Iraqis by June 30.

The US military said yesterday's attack occurred about 7.40am when a car drove into the new Iraqi army facility in central Baghdad and exploded.

One of the injured, Ghassan Samir, said: "We were standing in line waiting to start our shift in the new army and we saw a white car drive by us and then blow up. Many died. There were about 400 people in line."

Mohammad Jassim said: "I was driving and just 10 metres in front of me, a car was driving slowly, suddenly he exploded... I hit a tree."

US troops cordoned off the area known as Muthana Airport, a small airfield abandoned for decades but recently used by the new Iraqi army.

Heavy rain and wind buffeted emergency workers, investigators and soldiers as they did the grim work of cleaning up.

The attacks followed a pattern of targeting Iraqis seen as collaborating with the US occupation. Twin suicide bombings in northern Iraq against two Kurdish parties allied with the US killed more than 100 people on February 1.

Tuesday's suicide car bomb exploded among civilians queueing outside a police station in the town of Iskandariya, 40 kilometres south of the capital, to apply for jobs.

At least 75 people were injured and the police station and an adjacent court building were badly damaged.

Iraqi officials say that 300 policemen - who have been regular targets of suicide bombings - have been killed by insurgents.

The US-trained force is a pillar of plans to put Iraqis in charge of security before a transfer of sovereignty.